This invention relates to the selective hydrodenitrogenation (HDN) of raw oils, and more particularly to the use of sulfided carbon supported Fe--Mo catalysts to selectively hydrodenitrogenate hydrocarbon feedstocks.
Hydrodenitrogenation (HDN) is one of the most important reactions that take place during hydrotreating/hydroprocessing. Nitrogen compounds, if not removed, effectively poison the acidic fluid catalytic cracking (FCC), reforming and hydrocracking catalysts downstream. The importance of HDN has been steadily growing in recent years due to a variety of environmental and economic reasons.
HDN is much more difficult compared to other reactions such as hydrodesulfurization (HDS) and hydrodeoxygenation (HDO) that take place simultaneously during the hydrotreating operation. This is the reason why some industrial hydrotreating process conditions are dictated by the capability of the catalyst to remove nitrogen (nitrogen specification). So, catalysts that are more efficient for HDN are advantageous for the refining industry.
Conventional hydrotreating catalysts consist of different combinations of Mo or W promoted by Co or Ni, supported on alumina, with or without some additional promoters. All these catalysts are significantly more active for HDS than for HDN at any given reaction condition.
The carbon supported Fe--Mo catalysts of the present invention are as effective for HDN as they are for HDS. This indicates that the selectivity of these catalysts for Carbon-Nitrogen bond breaking (for HDN) is much higher than those of the conventional alumina supported hydrotreating catalysts. This is an unusual and useful property for a hydrotreating catalyst.
It is an object of the present invention to provide a catalyst system which would serve to selectively remove nitrogen from hydrocarbon feedstocks, i.e., the hydrodenitrogenation (HDN) of raw hydrocarbon oils.